You'll have plenty of time to give them a try! Adding the grid screen is a good idea. I did that with my E1. Fortunately, the E1 grid screen was user-interchangeable so I did it myself.

Apparently for the E3, E5, and E30 the focus screen is somehow coupled to the exposure metering. Rebecca Katz' folks say it's difficult for a normal user to change the screen and worse, if you add their split-image version the metering is affected. The Oly grid screen doesn't do that and they're charging me $70 for the screen + installation plus another $10 for return shipping so when you add the $10 to ship it to them I'll have that screen in place for under $100. I shipped it on the 10th by UPS ground, they received it on the 11th and said they'd ship it back by the 17th - you can't complain about that. I'd rather have a screen with a split-image plus grid but since that's not gonna happen I think I'll be happy with the FS-3 - using the row of AF points doesn't help me that much since as often as not I'm trying to keep vertical lines orthogonal. But I'll let you know when I get it back.